Milady Chapter 11 - Properties of the Hair and Scalp

Polypeptide Chain

A long chain of amino acids linked by peptide bonds.

Dermal Papilla

A small, cone-shaped elevation located at the base of the hair follicle that fits into the hair bulb. It contains the blood and nerve supply that provides the nutrients need for hair growth.

Disulfide Bond

A strong, chemical side bond. They are not broken by water. They are broken by perm waves and chemical hair relaxers that alter the shape of the hair. They are not broken by normal heat. They are broken by extreme heat.

Cowlick

A tuft of hair that stands straight up.

Hydrogen Bond

A weak, physical, cross-linked side bond that is easily broken by water or heat. They reform when the hair dries or cools. (wet set)

Salt Bond

A weak, physical, cross-linked side bond. This bond depends on pH, so they are only broken by a strong change in pH whether alkaline or acidic. They are reformed by normalizing the pH level.

Alopecia

Abnormal hair loss.

Alopecia Areata

An autoimmune disorder that causes the affected area of hair follicles to be mistakenly attacked by a persons own immune system.

Carbuncle

Bacterial infection. Similar to a furuncle but larger.

Furuncle

Bacterial infection. Technical term for a boil. It is a localized infection of the hair follicle and produces a pustule perforated by a hair and causes constant pain.

Side Bonds

Bonds that keep polypeptide chains together. They help make the cortex and due to their bonds give hair its extreme strength and elasticity. There are three types.

COHNS elements

Carbon (51), Oxygen (21), Hydrogen (6), Nitrogen (17), Sulfur (5).

Pityriasis Capitis Simplex

Classic dandruff. Scalp irritation, large flakes, and itchy scalp.

Alopecia Universalis

Complete body hair loss.

Pityriasis

Dandruff. Excessive production and accumulation of skin cells.

Hypertrichosis

Hair Disorder. Abnormal terminal hair growth in areas of the body that normally grow vellus hair. AKA hirsuties.

Ringed Hair

Hair Disorder. Alternating bands of gray and pigmented hair through the length of the hair strand.

Monilethrix

Hair Disorder. Beaded hair. Hair breaks easily between beads or nodes.

Fragilitas Crinium

Hair Disorder. Brittle hair.

Trichorrhexis Nodosa

Hair Disorder. Knotted hair. Characterized by brittleness and the formation of nodular swellings along the hair shaft.

Trichoptilosis

Hair Disorder. Split ends.

Canities

Hair Disorder. Technical term for gray hair. Hair without pigment. Can be congenital - exists at or before birth. Can be acquired - develops with age.

Hair stream

Hair flowing in the same direction, resulting from the follicles sloping in the same direction.

Androgenic Alopecia

Hair loss that is characterized by terminal hair turning into vellus hair. It is caused by genetics, age, or hormonal changes.

Whorl

Hair that forms in a circular pattern as on the crown of the head.

Hydrophobic

Hair that is naturally resistant to being penetrated by moisture.

Proteins

Long coiled chains of polypeptides (which are long chains of amino acids linked by peptides).

Terminal hair

Long, coarse, pigmented hair found on the scalp, legs, arms, and bodies.

Hair density

Measures the number of individual hair strands on 1 square inch of the scalp. Low (thin), medium, or high (thick).

Sebaceous Glands

Oil glands in the skin that are connected to hair follicles.

Scabies

Parasite. Highly contagious skin disease caused by a parasite called a mite that burrows under the skin.

Pediculosis Capitis

Parasite. Infestation of the hair and scalp with head lice.

Hydrophilic

Porous hair that has a raised cuticle and easily absorbs moisture.

Keratinization

Process by which newly formed cells in the hair bulb mature, fill with keratin, move upward, lose their nucleus, and die.

Pheomelanin

Provides natural colors to hair ranging from red and ginger to yellow and blonde tones.

Eumelanin

Provides natural dark brown to black color to hair.

Wave Pattern

Refers to the shape of the hair strand. Is described as straight, wavy, curly, or extremely curly.

Telogen Phase

Resting phase. When the fully grown hair is shed. About 10% of hair is in this phase at any given time.

Pityriasis Steatoides

Severe dandruff. Greasy or waxy scales mixed with sebum that stick to the scalp in crusts.

Vellus hair

Short, fine, unpigmented, and downy hair that appears on the body. Found in places that are normally considered hairless (ex: forehead, eyelids, bald scalp). AKA lanugo hair.

Arrector Pili Muscle

Small, involuntary muscle in the base of the hair follicle. It makes hair stand up straight (goosebumps).

Postpartum Alopecia

Temporary hair loss experienced at the end of a pregnancy.

Hair porosity

The ability of hair to absorb moisture. Low (resistant), average (normal), or high (overly porous).

Hair elasticity

The ability of hair to stretch and return to its original length without breaking.

Medulla

The innermost layer of hair. Very fine and very blonde hair sometimes will not have this layer. Usually only thick, coarse hair has it.

Hair Bulb

The lowest part of a hair strand. The thickened club-like structure that covers the dermal papilla.

Cortex

The middle layer of hair. It is a fibrous protein core formed by elongated cells containing melanin pigment. The elasticity of hair and its natural color are a result of this layer.

Cuticle

The outermost layer of hair. It provides a barrier that protects the inner structure of the hair. It creates shine, and the smooth, silky feeling of hair.

Hair Root

The part of the hair located below the surface of the skin.

Hair Shaft

The portion of the hair that projects above the skin.

Trichology

The scientific study of hair and its diseases and care

Cross- Section

The shape of the diameter of the hair strand. Straight hair is more round, while curly hair is more oval-like and flat.

Helix

The spiral shape of a coiled protein. It is created when polypeptide chains intertwine.

Peptide Bond

The strong, chemical bond that joins amino acids. AKA end bonds.

Hair texture

The thickness or diameter of the individual hair strand. Coarse, medium or fine.

Hair Follicle

The tube-like depression or pocket in the skin that contains the hair root.

Lanthionine Bond

This is what disulfide bonds are converted to when a hydroxide relaxer is used on them.

Melanin

Tiny grains of pigment in the cortex that give natural color to hair.

Alopecia Totalis

Total scalp hair loss.

Catagen Phase

Transition period. It is between the growth and resting phases. The follicle shrinks and detaches from the dermal papilla.

Amino Acids

Units that are joined together end to end like pop beads.

Anagen Phase

Growth phase. New hair is produced. Normal hair grows about 1/2 in per month (6 in per year). About 90% of hair is in this phase at any given time.

Minoxidil

FDA approved medication that is put on the scalp to stimulate hair growth.

Finasteride

FDA approved oral prescription medication for men only that helps stimulate hair growth.

Tinea Favosa

Fungal infection. Dry, sulfur-yellow, cup-like crusts on the scalp called scutula.

Tinea Capitis

Fungal infection. Fungal infection of the scalp. Characterized by red papules, or spots at the opening of hair follicles.

Tinea

Fungal infection. Ringworm. Itching, scales, painful circular lesions. Caused by a fungal organism. It is contagious.

Tinea Barbae

Fungal infection. The most frequently encountered fungal infection resulting from hair services. Deep inflamed, or non inflamed patches of skin on the face or nape of the neck. AKA barber's itch.

Malassezia

Fungus that is present on all human skin but causes the symptoms of dandruff when it grows out of control.